Magar of the Magic Strings, Day's Undoing, and Last Chance

Prerequisites

• Magar of the Magic Strings on the battlefield
• Day's Undoing in the graveyard
• Last Chance in hand
• available

Steps

1. Cast Last Chance by paying its mana cost, causing you to take an extra turn after this one and to lose the game at the beginning of that turn's end step
2. Activate Magar by paying , noting Last Chance and putting it face down on the battlefield as a 3/3 creature
3. Activate Magar by paying , noting Day's Undoing and putting it face down on the battlefield as a 3/3 creature
4. During your next turn, deal combat damage to an opponent using the face down creatures that have Last Chance and Day's Undoing noted
5. The creatures trigger
6. Resolve the first trigger, casting a copy of Last Chance without paying its mana cost
7. Resolve the copy, causing you to take an extra turn after this one and to lose the game at the beginning of that turn's end step
8. Resolve the second trigger, casting a copy of Day's Undoing without paying its mana cost
9. Resolve the copy, causing you to end the turn
10. This will prevent the Last Chance trigger from causing you to lose the game
11. Repeat from step 3

Results

• Infinite turns